The present invention relates to a receptacle for launching light into a light guide formed from, for example, a fiberoptic bundle or a tube filled with a liquid.
There are presently two types of instruments used to visually inspect internal surfaces in objects which an inspector cannot see without disassembling or cutting apart the object, the fiberscope and the videoscope. Both these instruments are flexible. The fiberscope employs a coherent fiberoptic image bundle to relay an image from an objective lens at a distal tip of the instrument back to the eyepiece. The videoscope differs in having a miniature CCD chip television camera at its tip to relay the image. Another instrument is the borescope which is a rigid instrument with a series of lenses similar to a telescope. The present invention applies to all three of these instruments.
These instruments use a light guide to transmit light from an external light source unit through the instrument to illuminate the internal area to be inspected. These external light source units can use a variety of lamps such as an incandescent tungsten filament bulb or a gas discharge lamp as the source of light. These light sources also generate tremendous amounts of heat in the form of infrared radiant energy. The lamp reflector focuses the heat as well as the light onto the metal tip area of the light guide plug and the receptacle holding it. The temperature can become excessive and cause the epoxy binding the glass fibers to burn, melt and discolor, and thus destroy the light transmission of the light guide. Moreover, serious burns to the fingers can result if the operator does not follow instructions, ignores safety cautions and handles the tip of a light guide just after removing it from the light source. The build-up of heat on the tip is often sufficient to cause serious burns on the fingers. The hot light guide tip can also present a fire hazard if mistakenly placed on flammable material.
The trend in the industry is toward using video displays with smaller diameter instruments in which the light guides carry more light. This trend requires higher intensity light sources such as metal halide gas discharge lamps or xenon gas discharge lamps for visible light and mercury gas discharge lamps for ultraviolet illumination. All of these lamps produce enormous amounts of heat. These higher intensity light sources can make the metal tip of light guides and the metal receptacle much more prone to reach excessive temperatures.